California launched a legal battle with U.S. railroads Thursday that, if successful, could improve the health of people who live near train yards in Chicago.

The California Air Resources Board voted unanimously to require railroads to cut diesel soot emissions from passenger, freight and industrial locomotives by 91% by 2050 and to slash smog-forming nitrogen oxides, or NOx, by 86%.

When it comes to diesel soot, “there is no acceptable level of exposure,” Cari Anderson, branch chief for freight at the Air Resources Board, said in an interview.

Illinois stands to benefit from what California is doing, even though the state won’t be conducting its own legal crackdown. Three-quarters of the 16,000 locomotives at BNSF pass through California as they circulate nationwide, Anderson said.

As California cleans them up, many will find their way back to Chicago along the railroad’s busiest intermodal route, the Southern Transcon, which begins in Los Angeles.

To achieve California’s goals, the railroads could initially use technologies that are already commercially available. Beginning in 2030, they’d have to begin switching to zero-emission locomotives.

According to the Air Resources Board, only 4.8% of locomotives operating in California use the latest, so-called Tier 4 emission controls that have been on the market since 2015. Many others began operating in the 1950s, and some emit 20 times more diesel soot than the most up-to-date models.

According to Maria Castaneda, spokeswoman for the state’s Department of Transportation, Illinois does not maintain a roster of locomotives operating inside its borders. As a result, Springfield doesn’t know how many employ Tier 4 emission controls and how many release toxic plumes that are much more dangerous.

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Illinois has no plans, Castaneda said, for a legally binding mandate like California’s.

But Illinois does focus on voluntary programs like CREATE, or the Chicago Region Environmental and Transportation Efficiency Program. CREATE uses public and private funds to eliminate bottlenecks in rail infrastructure.

By relieving traffic congestion, Castaneda said, CREATE is reducing the impact of cars, trucks and trains on the Chicago environment. The state takes “a lot of pride” in saying that Chicago-area companies handle a quarter of the nation’s freight, IDOT Secretary Omer Osman said during an event at Malcolm X College earlier this month.

Meanwhile, with the new rules, California expects to avoid over 3,200 premature deaths, cut cancer risks from locomotive emissions by more than 90%, and save $32 billion in unnecessary hospitalizations and other health costs.

That’s more than double the cost of implementing the new rules, according to the Air Resources Board.

California is also helping the railroads tap billions of dollars in state and federal grants to develop reduced- and zero-emission technologies. Many of these grants are targeted at neighborhoods with dense concentrations of freight traffic.

Anderson said California is cracking down on locomotives in part because it’s already limiting emissions from all other types of freight-moving vehicles.

For example, California has or is moving to enact zero-emission requirements for short- and long-haul trucks, overhead cranes, forklifts and other types of cargo-hauling equipment.

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Even if California’s new locomotive rules do benefit Illinois in the long run, the immediate impact could be harmful.

That’s because the modernization of California’s fleet could increase the supply of used locomotives for small railroads, switching yards and factories in other states, including Illinois.

“There could be a race to the bottom, where these (old) locomotives go to the least-regulated areas,” said DePaul University transportation professor Joseph Schwieterman.

To prevent such a race, Schwieterman said, Illinois should join a multistate coalition to limit locomotive emissions.

Illinois could have time to prepare for such a step.

Michael Rush, a spokesman for the Association of American Railroads, told California officials in November that the new rules will result inevitably in lawsuits and court orders blocking their implementation.

He said that federal laws governing both clean air and interstate commerce “preempt” states’ ability to regulate railroad emissions.

California officials not only believe they can defend their new emission limits from such a lawsuit but also plan to work with the U.S. Environmental Protection Agency to advocate for a similar measure nationwide. In a November letter to California, the EPA promised to consider new rules to ensure that federal preemption laws don’t “inappropriately limit” the ability of states to defend their air quality.

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For now, any action the railroads take is voluntary.

Two years ago, for example, Norfolk Southern committed to reducing greenhouse gas emissions from its operations by 42% by 2034, spokesman Connor Spielmaker said.

At its 47th Street yard in Chicago, Spielmaker said, Norfolk Southern is pursuing this goal with diesel-electric cranes, rebuilt engines with updated pollution controls for in-yard locomotives and an additional track that reduces idling.

In its systemwide Environmental, Social and Governance Report for 2022, Norfolk Southern noted a 2.7% annual drop in NOx emissions and a 1.9% reduction in PM10, a component of diesel soot.

But the railroad is fighting an uphill battle. Two years ago, the U.S. Department of Transportation predicted that the nation’s freight activity would increase 50% by 2050.

John Lippert is a freelance reporter.